Electrical apparatus



Jan. 7, 1941. w J LARKiN, JR' 2,228,138

ELECTRICAL APPARATUS Filed April 26, 1940 Patented Jan. 7, 1941 I I l UNITED STATES PATENT OFFICE 2,228,138 ELECTRICAL APPARATUS William J. Larkin, Jr., Lynnfield, Mass, assignor to National Company, Inc., Maiden, Mass, a corporation of Massachusetts Application April 26, 1940, Serial No. 331,776

4 Claims. (Cl. 173-269) My invention relates to electrical apparatus the cap l may be constructed in any convenient and consists in an improved safety cap for high manner, but I prefer to mold it from a thermovoltage terminals. setting insulating material, such as mica-filled The most important object of my invention is Bakelite, electrical porcelain, polystyrene, or to provide an insulated connector cap for the any other thermo-plastic material of very high end of a wire leading to the grid or plate terresistance. One end of the cap body Ill is larger minal of a high voltage vacuum tube, which than the other and substantially cylindrical in will permit the operator to make or break the shape, and the cap tapers in both width and connection while current is flowing without any height toward its other end. In the large end 1 danger of touching conducting material and of the cap is a cylindrical well or socket 12 which with entire safety to himself. High voltages are may be termed the terminal-receiving well. The often used in radio transmitting equipment and Well l2 extends inwardly through the bottom in various industrial apparatus, and severe in- Wall of the cap, and a second and somewhat juries or even death by electrocution have re smaller well i4 is disposed adjacent thereto and 15 suited when the operator of the apparatus has also extends inwardly through the bottom wall accidentally come in contact with a terminal of the cap Ill. The smaller well M may be while the current was flowing. The connector termed the soldering well and is provided with cap of my invention is well calculated to elimian inner wall sloping outwardly so that the 30 nate such accidents. deeper part of the soldering well it lies in An important feature of my invention resides the side opposite to the terminal-receiving well in an insulating cap containing a one-piece i2. The end wall of the cap NJ is pierced as metal contact member one portion of which is shown at I6 and a bushing l8 of insulating maarranged to fit over the terminal to which the terial is tightly fitted into the hole 16 extending connection is made and another integral por- P l to t bottom face of the p d at an tion of which is formed as a soldering lug. obtuse angle to the inner slop Wall Of the A striking advantage resulting from the con- Soldering well. struction of my invention comes from the ease As shown in Figthe cohtaet er 2" with which one or more wires may be slipped is cut from a strip of flat resilient sheet metal. in place nd old d to th ntact ber The dotted lines indicate the places where the referred t abov flat cut-out blank is to be bent. At one end These and other objects and features of my the blank s reduced t form a narrow 1 invention will be more readily understood and and 5 23 a e Gilt Out Of the y p o o appreciated from the following detailed descripthe l t e blank is also reduced adjacent its tion of a preferred embodiment thereof, selected Other end to form n w ec 3 a d r' for purposes of illustration and shown in the broader throat p on 3 ter the blank has a accompanying drawing in whichbeen cut out, it is bent into the shape shown Fig. l is a view in cross section showing the in Fig 5- It Wil be Seen that the finished safety cap of my invention applied to the grid Contact member 20 s a l t top 25 and int rminal f e, vacuum tube, Wardly bowed sides 30. The cars 28 are (11- 4O Fig. 2 is a view in perspective of the safety cap d downwardly and outwardly a d e reas seen from below, silient. The lug 32 is bent outwardly, the neck Fig. 3 is a bottom plan view of the insulating 34 is bent to form an acute angle with the adcap with the metal contact member removed, jacent side 30, and the throat p o 6 is 00D- Fig, 4 is a plan i w of th m t l t t caved to form a dished or channel-shaped sol- 45 member after it has been cut from strip metal dering 11 and before it is bent, to shape, The sides of the terminal-receiving well I2 Fig. 5 is a view in side elevation showing the are provid w h pp y disposed, v r ic l t t t, member after it h b shaped channels 44 dimensioned to receive the sides 30 and of the contact 20. Smaller channels 46 are 50 Fig. 6 is a View in cross section of an alterout into the channels 44 and receive the resil- 50 native form of cap. ient ears 2B. The larger channels 44 prevent the As shown in the drawing, the safety cap of member 20 from rotating in the well l2 while the my invention consists essentially of two elecars 28 engage the sides of the smaller channels 5r) ments, an elongated outer insulating body I0 46. Since the ears 28 are slanted downwardly,

and a metal contact member 20. The body of they act as resilient barbs and resist separation of the member 20 from the cap Ill. The lug 32 acts in the same way as the ears 28.

The neck 34 of the contact 20 fits into a recess 48 cut into the wall of the cap which separates the wells I2 and I4, and the throat 36 lies on, or parallel to, the inclined inner wall of the Well M.

Fig. 1 illustrates the application of a cap to the grid terminal 24 of a vacuum tube 22. It will be evident that the insulating cap l0 completely covers the terminal 24 so that no conducting material is exposed. Those skilled in the art will recognize that the only exposed conducting material in a vacuum tube of the type illustrated is the grid or plate terminal and the contacts in the base which are nearly always under a protecting panel or chassis.

The wire 40 is covered by insulation 38, and in connecting the end of the wire to the cap a small section of the insulation 38 is stripped away to expose a length of the bare wire. When the wire is inserted through the hole IS in the cap Ill, the end of the wire 40 strikes the inclined throat 36 and is bent outwardly at an angle so that the exposed end portion of the wire lies snugly in the concave throat 3G. The bare portion of the wire 40 is entirely within the cap. The sides of the throat 36 may be closed around the wire 49, and a drop of solder 42 applied to make a firm connection. The wire may be disconnected, should occasion arise, by heating the solder and pulling out the wire. The ease and rapidity with which the cap may be connected to a wire is a striking feaure of my invention.

The ears 28 hold the contact member 20 in the cap 10 so that the cap may be removed from the terminal 24 without loosening the contact or separating it from the cap. The bowing of the sides 30 of the contact renders them resilient in order that they may firmly grip the terminal 24 and establish a good electrical contact. The fact that the soldering lug or throat 36 is integral with the contact proper is advantageous, inasmuch as it eliminates a further joint in the circuit.

An alternative form of cap is shown in Fig. 6, where a molded insulating cap is provided with a terminal-receiving well 62 precisely similar to the well I2. Another well 64 is disposed adjacent the well 62 and is provided with a sloping inner wall. An outlet 66 leads laterally from the well 64, and the bushing may be omitted if desired. In the top of the cap 60 is another outlet 68 leading into the well 64. The contact member is not illustrated, since it may be similar to the contact 20. The cap 60 permits two wires to be connected to the contact member, one wire entering the outlet 68' and the other coming in the outlet 68. Otherwise the cap functions like the cap I0. Both outelts 66 and 68 are so placed that the bare end of an entering wire is automatically directed into soldering position on the throat of the contact member.

I have now described with particularity an improved safety cap for high voltage terminals. It is important to note, in using the cap of my invention, that the terminal-receiving well and the contact member are so constructed and arranged that the entire terminal is covered by the insulating material of the cap and no conducting or live material is exposed. Furthermore the contact 20 is entirely within the confines of the cap and is not exposed. The result is that when the apparatus is in use, the operator can make adjustments or inspect the apparatus without danger of accidentally coming in contact with current carrying material. In addition, the

configuration of the throat of the contact member automatically brings the bare end of the wire in position to be clamped and soldered firmly in place, no screws or separate clamps are necessary, so that the cap and the contact member may each be formed in simple shaping operations, no screw threading or other treatment being required.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. A device of the class described, comprising an insulating cap having a terminal-receiving Well and a soldering well in side by side relation in one wall, the soldering well having a bottom wall inclined with respect to its sides, a wirereceiving outlet in another wall of the cap leading from said soldering well and disposed at an angle to the bottom wall of the said well, a metal contact member disposed in the terminal-receiving well and extending into and. along the bottom wall of the soldering Well, whereby a wire inserted through said outlet strikes the contact member and is automatically deflected and bent to lie on the contact member in soldering position.

2. A device of the class described, comprising a molded cap of insulating material provided in one wall with a terminal-receiving well and a soldering well separated by a recessed wall, said soldering well having a bottom wall inclined with respect to its sides, a wire-receiving outlet formed in another wall of the cap and entering the soldering well at an obtuse angle with respect to said inclined wall, and a metal contact member disposed in said terminal-receiving well and having a neck fitting the recess in said separating wall and a concaved throat portion disposed on said sloping wall, whereby a wire pushed through said outlet will strike said throat portion.

3. A cap of insulating material provided with a terminal-receiving well and a soldering well in side by side relation in one wall thereof separated by a recessed wall, the bottom wall of the soldering well being slanted down and away from the recessed wall separating the wells, an outlet in another wall of the cap adjacent the deepest portion of said soldering well and disposed at an obtuse angle with respect to said slanted wall, and a contact member comprising a strip of sheet metal bent to follow the contours of the terminal well, and having a neck fitting in the recess of the separating wall and having a concaved throat portion lying along the slanted inner wall of the soldering well.

4. A safety cap for terminals, comprising an insulating body having a cylindrical terminal well in one of its walls, opposed channels in the sides of the walls of the well, narrower channels in each of the opposed channels, a second well adjacent the cylindrical well, a contact member comprising a strip of sheet'metal following the contours of the cylindrical well and disposed in said opposed channels, wings cut from said strip and engaging the sides of the narrower channels, and a throat portion integral with the strip and disposed in the second well.

WILLIAM J. LARKIN, JR. 

